/*
 * Copyright (2023) The Delta Lake Project Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package io.delta.kernel.internal.lang;

import java.util.Optional;
import java.util.function.Supplier;

public class Lazy<T> {
  private final Supplier<T> supplier;
  private Optional<T> instance = Optional.empty();

  public Lazy(Supplier<T> supplier) {
    this.supplier = supplier;
  }

  public T get() {
    if (!instance.isPresent()) {
      instance = Optional.of(supplier.get());
    }

    return instance.get();
  }

  public boolean isPresent() {
    return instance.isPresent();
  }
}
